However, while it was known that Barclays was under scrutiny, the alleged loan to the Qataris represents a new element of the investigation, according to reports. How much was allegedly loaned, and to what bodies, is unclear.

The controversial capital raising push in 2008, when the crisis was at its worst, had seen Barclays raise billions of pounds from investors in Qatar and Abu Dhabi, meaning that it avoided taking emergency funds from the Government.